Skull: Headwork part 1: positioning notes & image critique

Skull ROUTINE views

AP axial towne

PA axial caldwell

Right & left laterals

Skull 3 views or less charge

AP/PA & left lateral

AP axial towne technique

85 kVP @10 mAs, center cell

PA axial caldwell technique

85 kVp @7.1 mAs, center cell

Lateral skull techniques

85 kVp @3.2 mAs, center cell

AP axial towne overview:

• 10×12 LW

• MSP is perpendicular to midline of the IR, flex pt neck so OBML is perpendicular to the plane of the IR. Position IR so its upper margin is at the level of the highest point of the vertex

• angle 30 degrees caudad to OML (or 37 to IOML)

• center 2.5” above glabella & pass through the EAM

• R or L marker

if patient has difficulties flexing neck far enough to get OML perpendicular in AP axial towne, do this

place IOML perpendicular

breathing for all of headwork

suspended respiration

what view does this purpose describe: “symmetric image of petrous pyramids, the posterior portion of the foramen magnum, dorsum sellae and posterior clinoid processes projected WITHIN THE FORAMEN MAGNUM, the OCCIPITAL BONE, and the posterior portion of the parietal bones”

ap axial towne

AP axial towne criteria:

1. entire cranium w/o rotation or tilt demonstrated by:

• equal distance from lateral border of skull to lateral margin of foramen magnum on both sides

• symmetric petroud pyramids

• MSP of cranium aligned w/ long axis of collimated field

2. dorsum sellae & posterior clinoid processes visible within foramen magnum

AP axial towne help:

• if you turn the head, the foramen magnum goes in the OPPOSITE direction

• THE LONGER SIDE ON THE AP IS THE WAY THE HEAD IS TURNED!!

Ex:

(if there is longer distance from the foramen magnum to the R, the head is turned to the R)

occipital bone is best visualized on what skull view?

AP axial towne

if you see a “bridge” within the foramen magnum this means

over tucking or too much tube angle (posterior arch of C1 is visualized)

if you cannot see the foramen magnum clearly, this indicates

not enough angle or not enough chin tuck

if you have the foramen magnum but it is not clear, this indicates

not enough angle or not enough tuck

degree differences for skull views

1. 30 (ap axial towne)

2. 15 (pa axial caldwell)

3. 0 (lateral)

4. 0 (lateral)

frontal bone is best visualized on what view

PA axial caldwell

PA axial caldwell overview

• 10×12 LW

• flex pt’s neck so OML is perpendicular to the plane of the IR (generally, the patient’s forehead & nose will be resting against the IR). MSP perpendicular to the IR

• check for rotation by feeling the mastoid tips

• center 15 degrees caudad exiting the nasion

• R or L marker

what view has the purpose of petrous pyramids within the lower third of the orbits, the anterior & posterior ethmoidal air cells, crista galli, frontal bone, and frontal sinuses

PA axial caldwell

PA axial caldwell evaluation criteria

1. entire cranium w/o rotation or tilt demonstrated by:

• equal distances from lateral border of the skull to the lateral border of the orbits on both sides

• petrous ridges should be symmetric

2. entire cranial perimeter showing 3 distinct tables of squamous bone

if petrous ridge is at top of orbits in a PA axial caldwell, this indicates

chin is tucked too much or not enough angle

if you want the petrous ridges to come down, what can you do?

bring chin up or increase the angle

if you want petrous ridges to come up higher because they are too low, what can you do?

tuck chin or decrease angle

PA axial caldwell helpful hint

• shorter distance side from foramen magnum is the side it is rotated towards

bilateral laterals overview

• 12×10 CW

• place PT in anterior oblique, MSP must be parallel to IR, flex PT neck so IOML is perpendicular to front edge of IR & parallel to IR long axis. the interpupillary line should be perpendicular to IR

• center 2” superior to the EAM

• mark side closest to IR & anterior to pt

what view shows superimposed halves of the cranium showing the detail of the side AGAINST the IR. the sella turcica, anterior clinoid processes, dorsum sellae, and posterior clinoid processes are visualized

bilateral laterals

biltateral laterals evaluation criteria

1. entire cranium w/o rotation or tilt demonstrated by

• superimposed orbital roofs & greater wings of sphenoid

• superimposed mastoid regions & EAMs

• superimposed TMJs

• sella turcica seen in profile

2. no overall of cervical spine on mandible

rotation on bilateral laterals example (if you can see the mandible)

the side that is magnified is the side that is farthest away

Skull special view PA (no angle) purpose

frontal bone is area of interest

• orbits are filed by petrous ridges

what special skull view is this?

PA no angle

skull special view: SMV full basal

• hyperextend neck so IOML is nearly parallel w/ IR, rest head on its vertex, & adjust head so MSP is perpendicular to IR

• direct CR through sella turcica perpendicular to the IOML between the angles of the mandible ( ¾” anterior to EAM)

what special view of the skull is this?

SMV full basal

skull special view: trauma x-table lateral

• 12×10 CW

• supine w/ head elevated on sponge

• MSP parallel to IR & IP is perpendicular to IR

• center 2” superior to EAM

• mark side against!!!

• visualize cranium details of side against IR

skull special view: recumbent (AP AXIAL, reverse caldwell)

• 10×12 LW

• center 15 degrees cephalad entering nasion

• SAME AS PA CALDWELL EXCEPT ORBITS ARE MAGNIFIED

skull special view: recumbent trauma AP

• center entering the nasion- NO ANGLE

• SAME AS PA EXCEPT ORBITS ARE MAGNIFIED

what skull special view is this?

recumbent AP axial/ Reverse caldwell

what skull special view is this?

recumbent trauma AP

skull special view: recumbent trauma AP axial towne

• angle CR to go through the OML, then add another 30 degrees, enter 2.5” above glabella

• ex: if pt is collared

what skull special view is this?

recumbent trauma AP axial towne